The invention relates to a deposited vertical semiconductor layerstack that serves to minimize surfactant behavior of n-type dopants, and the methods of making the layerstack.
During deposition of silicon, n-type dopants such as phosphorus and arsenic tend to seek the surface, rising through a silicon layer as it is deposited. If it is desired to deposit a layer having little or no n-dopant (an undoped or p-doped layer, for example) immediately above a heavily doped n-type layer, this tendency of n-type dopant atoms to diffuse toward the surface introduces unwanted dopant into the undoped or p-doped layer. This unwanted n-type dopant may adversely affect device behavior.
There is a need, therefore, to limit diffusion of n-type dopants in deposited silicon and silicon alloys.